Brake systems of vehicles, in other words of motor vehicles, are known. Vehicles can comprise a service brake system and a parking brake system. The parking brake system is used as a holding brake while the vehicle is parked for an extended period of time, for example, to prevent the vehicle rolling away whilst parked on a slope. Parking brake systems of this type are also described as hand brakes. The service brake system is used for braking the vehicle while the vehicle is in motion. The service brake systems comprise a brake lever as an actuating member that conveys a braking request from the driver to the respective operating members, in other words to the respective brake caliper having conventional components so that that the wheels and consequently the vehicle are/is braked. Known operating media that convey the necessary reactions from the brake lever to the respective operating members are, for example, brake fluids that are arranged in closed systems. The necessary pressure is generated by way of a master brake cylinder, wherein additional control systems such as ESP or ABS systems are known. Systems of this type are widely known and they will therefore not be discussed further. However, when transmitting signals remotely (brake by wire), a fall-back level for example of the hydraulic type is also provided for safety reasons.
However, regenerative systems are also known in which the braking energy is recaptured, wherein electrical energy can be generated and stored in an energy storage device. The electrical energy that is generated during the braking operation and thereafter stored can be conveyed as drive energy to the drive chain, wherein the electrical energy can also be fed into the on-board power supply in order to drive electrical energy consumers.
The actuating member can be a brake pedal that is actuated by a foot in order to brake the vehicle while the vehicle is in motion. A brake pedal sensation is set representing the relation between the factors of the brake pedal force to be applied and of the brake pedal travel in conjunction with the actual deceleration of the vehicle. However, the brake pedal sensation in the case of this dynamic requirement is not only dependent upon the aforementioned factors but also upon the vehicle behavior. By way of example, the vehicle obeying the laws of physics is inclined to dip at the front end, the extent of this dip becoming more pronounced the greater the deceleration and/or the more impulsive the deceleration becomes.
The vehicle will therefore be braked by way of the service brake systems. If the vehicle is temporarily stationary, for example at a set of traffic lights, the driver conventionally further actuates the service brake by way of the actuating member in order to maintain the stationary condition of the vehicle. The above mentioned factors, namely a deceleration and the vehicle behavior with respect to the dipping at the front end, are no longer discernible, so that the brake pedal sensation is only set in dependence upon the factors of the brake pedal force to be applied and the brake pedal travel. As is known, a so called “hard brake pedal” is set after a particular actuation time, in which case it is no longer possible for the driver to depress the brake pedal any further if the vehicle is stationary. The fact that an identical brake pedal sensation is always set while the vehicle is stationary is a direct result of the adjustment of the brake pedal sensation during the dynamic requirements, in other words if the vehicle is braked when the vehicle is in motion.